The present invention relates generally to crop harvesting machines containing a conditioning mechanism to condition crop material fed thereto and, more particularly, to a mechanism for spreading the upper and lower conditioning rolls apart when the crop gathering header is raised relative to the ground.
Mower conditioners typically include a crop gathering header which is normally provided with a cutterbar operable to sever standing crop material from the field, a conveying device, such as a rotating reel and/or an auger to convey the severed crop material rearwardly over the cutterbar, and a conditioning mechanism mounted rearwardly of the cutterbar to receive severed crop material from the reel or auger and effect a conditioning of the severed crop material to hasten the drying thereof. Although flail-type conditioners have enjoyed some success, conditioning mechanisms in North America generally include a pair of vertically spaced, counterrotating conditioning rolls operable to receive severed crop material therebetween to effect a conditioning thereof.
Because of varying thicknesses of materials passing between the counterrotating conditioning rolls, the upper conditioning roll has traditionally been mounted on pivot arms to permit a generally vertical movement of the upper conditioning roll toward and away from the fixed lower conditioning roll. To assure maximum engagement with the crop material to be conditioned, the upper conditioning roll is usually engaged with a biasing mechanism to urge the upper conditioning roll toward engagement with the lower conditioning roll. As the upper roll moves away from the lower roll, the biasing force is normally increased.
Under some situations, the amount of crop material passing between the counterrotating conditioning rolls is so great as to cause a plugging of the conditioning mechanism, which requires excessive torque to effect continued rotation of the conditioning rolls. In such situations, it is necessary to remove the crop material jammed between the conditioning rolls. To facilitate the removal of this material from between the conditioning rolls, it would be helpful to be able to raise the upper conditioning roll relative to the lower conditioning roll such as is generally taught in U.S. Pat. No. 4,174,600. However, it would be desirable to provide a device for manipulating the biasing forces exerted by the torsion bar on the upper conditioning roll to create reverse biasing forces urging the upper conditioning roll away from the lower conditioning roll without providing additional structure specifically for forcing the upper roll away from the lower roll by overcoming the biasing forces.